SEOUL (AFP) - A North Korean gulag survivor whose torture and daring escape was detailed in a best-selling book admitted he lied about details in his story, and said on Sunday he may end his campaign against human rights abuses.

Mr Shin Dong Hyuk, believed to be the only person born in a North Korean prison camp ever to have escaped, apologised on his Facebook page on Sunday, saying he had "forever wanted to conceal and hide part of my past".

Mr Shin recently changed some of the details in his story, Mr Blaine Harden, the book's author, said on his website. "On Friday Jan 16, I learned that Shin... had told friends an account of his life that differed substantially from my book," he said. "I contacted Shin, pressing him to detail the changes and explain why he had misled me."

Mr Shin told Mr Harden that some of the ordeals had been "too painful" for him to revisit and he had "altered some details" that he had thought would not matter, the Washington Post reported on Sunday. Mr Shin said he was "very sorry" in his Facebook posting.

"I... forever wanted to conceal and hide part of my past. We tell ourselves that it's okay to not reveal every little detail, and that it might not matter if certain parts aren't clarified," he said.

"To those who have supported me, trusted me and believed in me all this time, I am so very grateful and at the same time so very sorry to each and every single one of you," he said.

Mr Shin did not elaborate in the post on which part of his past had been fabricated.

Mr Shin was born and spent the first 23 years of his life in a prison camp where, he recounted in the harrowing Escape from Camp 14, he was tortured and subjected to forced labour before escaping in 2005.

Ever since, Mr Shin, now 32, has campaigned prominently to highlight rights abuses in the isolated North, testifying before a United Nations commission last year.

In Mr Harden's book, Mr Shin says he was brutally burned and tortured when aged 13, after a failed attempt to escape the camp.

But, according to the Washington Post, Mr Shin now admits the event took place when he was 20, the article said.

Mr Shin also said in the book he saw his mother and brother executed after he betrayed them, telling the authorities in Camp 14 of their plan to escape in hopes of getting food as reward.

But, said the Washington Post, the executions actually took place when he and his family were in a different camp.

Mr Lee Young Hwan, a Seoul-based rights expert, described the changes as "minor innaccuracies" and said many refugees who suffered abuse show "selective memory" due to mental trauma or an instinct for self-preservation that takes root during their years of ordeal.

"The trauma sometimes lead them to say only things that can work in their favour, or have jumbled memories about the most painful experiences," said Mr Lee, an adviser to the Citizens' Alliance for North Korean Human Rights.

"There may be minor inaccuracies in Shin's story, but his whole life and the nightmare he went through should still stand as evidence of history," he said.

On Facebook, Mr Shin said he "may not be able to continue" his years-long campaign against the North's regime, but urged his supporters to fight on.

"The world still needs to know of the horrendous and unspeakable horrors that are taking place," he said.

"These will be my final words and this will likely be my final post," he added, concluding with: "Thank You."

Mr Shin has been one of the most well-known campaigners against rights abuses committed in the North, where the Kim family rules its impoverished populace with an iron fist and pervasive personality cult.

The North has sought to discredit Mr Shin as a fabulist and criminal, and aired last October a TV interview with his father, who called Mr Shin a "liar" and denied the family was even in a labour camp.

Mr Shin argued that his father must have been coerced into denouncing him, saying he felt "suicidal" with guilt over the punishment his remaining family may have faced after his escape.